The present invention relates generally to wireless stereophonic speaker or headphone systems, and more particularly to base band signal treatment, local transmission and reception of electromagnetic signals therefor.
Audio and television equipment for home use is becoming increasingly complex, involving multiple programming sources capable of reproducing sound and data with ever increasing fidelity. In the past, speaker/headphone assemblies have been physically connected by cables to the receiver central receiver/player. Such arrangements are unaesthetic if the speaker/headphone is not located near the receiver/player because the wires connecting the speaker/headphone to the receiver/player may be visible. Installing wires under carpet or in the walls in order to hide them can be inconvenient and expensive. Also, wires can be unsafe for use in home entertainment systems in locations not proximate to the source of the acoustic data such as outdoors.
In the present art, traditional wireless headphones and other speaker assemblies employ the use of electromagnetic transmissions with low power to send data from the receiver/player to a receiver located at a speaker or a headphone, thus eliminating the need for the receiver/player and speaker/headphone to be connected by wire leads. Local low power single carrier signal transmission systems implemented in such a wireless headphone/speaker system usually operate within a frequency band of 902 MHz to 928 MHz using Frequency Modulated Multiplex Composite System (FM-MPX) signals. The FM-MPX signal in the single carrier signal transmission system includes the sum (R+L) and difference (L−R) of right and left audio channels in different frequency domains. When the signal is received, complete separation of the right and left audio channel is not feasible, resulting in inferior audio channel separation which deteriorates the stereo effect. Another drawback of such a conventional system is that the demodulation process at the receiver cannot completely eliminate a pilot tone used by the single carrier transmission system, and the residual noise of the pilot tone will distort the information in the transmitted signal. Also, the pilot signal consumes inordinate power, decreasing the efficiency of the transmitter.
Therefore, the use of traditional FM signals in a single carrier transmission system does not adequately reproduce the quality of sound that the receiver/player is capable of transmitting, thus forcing users to compromise the high fidelity of the signals in exchange for the convenience of having a wireless stereophonic headphone or speaker system.
What is needed is an improved method and system for transmitting stereophonic signals wirelessly.